It has been observed in the headwater of hydraulic reservoirs in hydro plants, especially in warm climates and in particular with hydraulic reservoirs of more than 15 m deep, that stratification of the headwater in the hydraulic reservoirs occurs, which originates a low dissolved oxygen level in the water. In particular, when the dissolved oxygen level in the water is below 5 mg/l, the aquatic life is directly impacted and the stress level of most fish increases dramatically. In such conditions, air is injected in the water passages of the hydraulic turbine of the hydro plant in order to increase the dissolved oxygen level contained in the water.
There are several techniques already known in the state of the art for injecting air in the water passages of a hydraulic turbine: however, each technique has a limited capacity to inject air in the hydraulic turbine, therefore leading to a different dissolved oxygen enhancement in the water. Furthermore, each of these techniques impacts the water pressure profile and the flow velocity streamlines inside the hydraulic turbine in a different way, which has an effect on turbine performances and characteristics.
Therefore, the existing solutions known in the state of the art injecting air in the water passages of a hydraulic turbine have limited air injection capability and have a high impact on the turbine performance.
The present invention is directed towards improving the above-mentioned existing limitations in the state of the art.